The Cameca MBX Microprobe has been interfaced to the DEC PDP 11/60 computer controlled Hitachi H700H TEM-STEM elemental imaging system. Elemental x-ray image acquisition is now possible on the microprobe with either the energy dispersive (EDS) or wavelength dispersive (WDS) detectors. In many cases the WDS detectors are preferred to the more efficient EDS detector because of their superior resolving power and high peak to background ratio. Also for many specimens an image magnification of 100x or 200x is most informative. At these magnifications the large area (1mm at 100x) which is digitally scanned results in WDS spectrometer defocussing relative to the source of the x-rays and thus artifactual variation in pixel intensity across the elemental images. In order to overcome the defocussing problem, software to dynamically focus both spectrometers in synchronism with the scanned electron beam was written. The 11/60 computer controls two Canberra Industries Axis Positioners using their Model 6726 Telecomputer Interface as the executive link. The spectrometer crystals are driven to the focussed positions for each beam location by controlling two positioner stepping motors. The focussed positioner settings are calculated from calibration files of beam coordinates at image limits and corresponding focused spectrometer settings obtained with standard specimens for each element of interest.